Method of determining power transmission.



L. N. MORSGHER. v METHOD OF DETERMINING POWER TRANSMISSION.

APPLICATION FILED APRLlS, 1&12.

Patented Dec. 29, 1914.

' NORRIS PETERS 170., PHOTO-LITHO. WASH/NO roN, D. C.

UNITED STATES PATENT OFFICE.

LAWRENCE N. MORSGI-IER, OF LAWRENCE, KANSAS, ASSIGNOR TO HIMSELF ANDIRVING HILL, A COPARTNERSHIP.

METHOD OF DETERMINING POWER TRANSMISSION.

Application filed April 15, 1912.

To all whom it may concern:

Be it known that I, LAWRENCE l. MoRsoHnR, a citizen of the UnitedStates, residing at Lawrence, in the county of Douglas and State ofKansas, have invented a new and useful Method of Determining PowerTransmission, of which the following is a specification.

I have discovered a new method of determining the amount of powertransmitted through a flexible transmission member, such as a belt,chain, cable, etc., through which the driving force is applied to thedriven object.

It has long been known that the speed of vibration of a flexible memberunder tension is dependent upon the character of the material, itsweight, the tension under which it is held, and its length betweensupports. If a driving force be applied to an object through the mediumof a flexible member such as a belt, and that flexible member betransversely vibrated, the speed of travel of the vibrations lengthwiseof the belt will be not only dependent upon the weight, tension andlength of the belt but, in addition, the speed of vibrations travelingin the direction of transportation of the belt will be greater than thespeed of travel of vibra tions in the direction opposite to thedirection of transportation of the belt by an amount equal to twice thevelocity of trans portation of the belt. Therefore, if the weight perunit length of the belt be known, its speed of transportation and itstension may be determined by a comparison of the speed of travel oflateral vibrations longitudinally of the belt. The tension of the belt,when reduced to pounds, multiplied by the velocity of transportation ofthe belt in feet per second, will indicate the power transmitted to theload. The speed of the lateral vibrations in the transmitting member maybe determined by means of airjets deflected by the passing lateralvibrations of the belt, the air jets impinging upon small vanes whichregulate electrical contacts; or by means of a beam of light cast by amirror and controlling a selenium cell; or by direct mechanicaloperation of markers by the vibrating belt, etc., and the apparatusillustrated diagrammatically in the accompany- Specification of LettersPatent.

Patented Dec. 29, 1914.

Serial No. 690,952.

ing drawings is therefore presented merely as an illustration.

The accompanying drawing illustrates diagrammatically a manner ofpractising my method or discovery.

In the drawing, 10 and 11 indicate a driving pulley and a driven pulley,respectively, connected by a belt having a tight side 12 and a slackside 13. Arranged adjacent to the tight side 12 of the belt at pointsseparated by a known distance are two electrical terminals 14 and 15.Arranged adjacent these terminals and normally out of contact therewith,are two terminals 14' and 15, respectively, which are interposed betweenthe terminals 14 and 15 and the tight side 12 of the belt, convenientlytrailing upon the belt. Similarly arranged adjacent the slack side ofthe belt are pairs of terminals 16, 16 and 17 17 separated from eachother by the same known distance as the distance of separation of theterminals 1 1 and 15. A record sheet 18 of any desired form is driven ata constant rate of speed by any suitable means, such, for instance, asthe clock-work 19 arranged so as to transcribe a time record 21 uponsheet 18 by a marker 22 of ordinary form in circuit with the clock-workin a common manner. Arranged in circuit with the pairs of terminals14-14, 15-45, 1616, and 17 17 are markers 14", 15, 16 and 17respectively, each arranged to transcribe its own particular record 23,24, 25, and 26, respectively, upon the record sheet 18. Supposing thebelt and pulleys to be in motion and the slack and tight sides of thebelt to be simultaneously struck so as to laterally vibrate at initialpoints exactly opposite the terminals 15 and 17 (or at uniform distancestherefrom on the side of the approach of the belt) the tight and slacksides of the belt will be set into lateral vibrations which will travellengthwise of the belt. These vibrations will cause simultaneousactuation of the terminals 15 and 17 so as to produce record markings Tand S, respectively, on the record sheet and these markings will be uponthe same radial line. The lateral vibrations in the belt will traveltoward terminals 14' and 16, respectively, and thus cause theproductions of record T and S,

respectively, on the record sheet, the angular space between the recordsT and T being less than the space between the records S and S becausethe speed of vibration in the tight side of the-belt will be greaterthan the speed of vibration in the slack side of the belt, due to thedifference in tension, and this difference in tension will be the onlycause tending to produce a difference between T and T and S and Sbecause the distances between the pairs of terminals are the same, theweight of the belt per unit length is constant and the velocity of thebelt for the short period required for the vibrations to travel from onepair of terminals to another may be considered constant even in caseswhere there is a material fluctuation in velocity of the belt. If nowthe tight and slack sides of the belt be struck in such manner that thevibrations will travel from one pair of terminals to the other in thedirection opposite to that of the travel of the belt between the pairsof terminals, a second set of records T T and S S will be produced, thedistance T T exceeding the distance T, T by an amount equal to twice thevelocity of the belt and the distance S S differing from the distance S,S by the same amount. Comparing these readings with the time record 21,the velocity of the belt may be determined and the difference in tensionbetween the tight and slack sides of the belt may also be determinedwhereupon, by multiplying the difference in tension by the velocity ofthe belt, the transmitted power may be determined. When the transmissionof power is by direct pull through a vibratory medium (not an endlessbelt) the transmitted horse power will be determined by multiplying thetension of the member by its velocity of transportation.

In the manipulation of the apparatus illustrated diagrammatically in thedrawing, it isnot essential that the tight and slack sides of the beltbe vibrated simultaneously or that the initial point of vibrations beexactly spaced with relation to the nearest set of terminals but bymanipulating the apparatus in the manner described the reading of therecord sheet is materially simplifled.

It is also possible, by a single indicator, to determine the rate ofvibration of the tight and slack sides of the belt due to the compoundaction of the travel of the belt and the weight, and the tension of thebelt and its velocity may thus be determined, but considerable morecalculation and more elaborate formulae will be required for thatpurpose.

The following description and formulae will clearly indicate thepractice of my improved, method The transverse waves of vibration in astretched flexible member and the longitudinal or sound waves in gasesand liquids travel similarly. The speed of propa gation of thesetransverse waves may be determined by methodssimilar to those used todetermine the velocity of sound waves provided proper means of detectingand recording the inaudible waves be used. For example, two personsstanding a known distance apart in line with a fort of unknown distance,each notes the time between his seeing the flash of a cannon and hishearing the report of the cannon; the difference between these separateresults giving the time required for the sound to travel past the firstman to the second man, for short distances the time required for thetravel of light being neglected. The time divided by the known distancegives the velocity of sound.

This corresponds to the two point method in which the chronographicrecord shows the time required for the belt wave to travel past onerecording point to another of known distance of separation. If these menhe in line between two forts in action with a swift wind blowingdirectly from one fort to the other, the men will observe that the soundtravels at a higher velocity with the windthan against it by an amountequal to twice the velocity of the wind, that is, if the wind velocitybe represented by X and the sound velocity by Y, then the velocity withthe wind will be Y plus X:C, while the velocity against the wind will berepresented by Y minus X D.

The velocities C and D being observed, the wind velocity X and soundvelocity Y become known. This corresponds to the two point method wherethe length of belt and speed of travel of the belt are unknown; beltspeed and wave velocity being both determined from the chronographrecord of waves passing each way past two detector points a knowndistance apart.

Another example: A man stands midway between two opposite parallelreflecting distant walls, whose distance apart is known. The man fires ashot, the sound of which is reflected past him from wall to wall atregular intervals, the echoes fom each wall passing him at coincidentregular intervals, if he be midway between the walls. This correspondsto the one point method where the detector is located in the middle ofthe belt span between the belt wheels, a wind blowing from one wall tothe other again corresponding to the belt travel. A variation is madeuse of Where the belt is struck over a divided detector point whichrecords both the blow and the wave reflected from the nearest supportingwheel, corresponding ;to' an echofrom a single wall. By a divided pointdetector I mean a detector with a finger on each side of the belt sothat whichever way the belt swings it will actuate the detector. When anundivided or single finger detector is used it is only effected by wavesin which the belt moves to the same side that the detector finger is on(the finger referring to the more commonly used electrical contactdetectors.) This much for getting the velocity of travel of thetransverse vibration. This reduced to equations becomes, for the twopoint method,-

where Vi the velocity of wave travel with the belt, Vd velocity of wavetravel against the belt, V=true wave velocity in the belt and S=thevelocity of travel of the belt itself.

Example: Two detector points ten feet apart on a belt gave a record of1/15 second of time for the wave to travel with the belt travel from onepoint to the other. 1/5 of a second was required for a wave to travel inthe reverse direction or against the belt travel from point to point.

10 1O 5-]- 15O+5O 200 2V.

V=100 feet per second or the rate of wave travel in the belt. 15050:100=2S=50 feet per second-:the rate of belt travel.

For the single point method, since the time which is recorded is the sumof the times a wave requires to travel with the belt travel and returnagainst this travel, the apparent velocity is the reciprocal of the sumof the reciprocals of the times taken to travel each way multiplied bythe distance traveled. If the single point method and single fingerdetector is used, then only every alternate reflected wave is recorded,since the direction of swing is reversed at each reflection of wave. Thetime taken to travel the distance (L) from one pulley to the otherpulley and back for the second reversal will be 2L V S Va T; In order tosimplify this calculatiomhowever, a set of tables might be prepared fromwhich V, the true belt velocity may be easily obtained by properreference to the V, and S obtained by measurements and the chronographrecord as above explained.

Further :To obtain the tension of the belt after V is obtained and W,the weight per unit length of belt, has been ascertained, it is onlynecessary to apply the well known formula for vibrating stretchedstrings:

where V=wave velocity, Fztension force and M:mass per unit length of thestretched string. If F be in pounds, V in feet per second and M be inpounds of weight per foot=W then where V is feet per second wavevelocity,

:pounds per running foot weight of string or belt and Fzthe pounds oftension. If the belt be traveling at the velocity S, it will transmit FSfoot pounds per second:

horsepow Sets of table may be preis again vibrated and the record takenas 1 before.

From well known laws of physics I have derived and by experiments provedthe correctness of the following formulae 71 M W a ii -1) where W=theweight per unit length of belt, M=the mass] by which the belt is loadedat its middle, T is the time required for the free unloaded belt to makea com.- plete vibration, t, the time required for the belt loaded at itsmiddle with the mass M, to make a complete vibration and L is the lengthof free belt span. Also 2L 2 W w e or in pound, foot, second system,

where F=the tension in pounds.

To summarize the one point method (using the English system of units forexample) determine the weight, W, of the belt in pounds per runningfoot, its rate of travel, S, in feet per second, the length of free beltspan L between support on belt wheels then apply the belt dynamometer toget the time, T, required for a complete vibration of the belt. f willgive the apparent velocity, V of wave in the belt, use the value of Vthus found in the formula Then F S=rate of work. If be in pounds, S andV in feet per second, and in pounds weight per running foot, then FXSwill be, in feet per second, FS

horsepower, much of this work, if so desired, being shortened by the useof a set of tables prepared as above mentioned.

T he two point method-Set the two detectors, L. feet apart against therunning belt where weight, W per foot is known, strike the belt in twoplaces so that two waves will pass the two points, one against the belttravel, the other with the belt travel, let T, and T represent the timeof travel respectively over the length L, then the rate of wave travel,as in the other example the tension in pounds in pounds tensions, whileV W.S. .03l

eqiials feet pounds per second rate of work or V WS. X.O0005636=:horsep0wer.

g (Equation 7) (Equation 4) (Eq at n (Equation 6) S (Equation 8) F V W(Equation 9) F S =rate of Work (Equation 11) rc M W m 1 (Equa ion 2) Vis the true transverse wave velocity through the stretched member. L isthe distance between two points of observation along the stretchedmember. T is the time required for the wave to travel the distance L. Lis the length of belt span between contact on pulleys. S is the velocityat which the belt is traveling. T is the time required for the wave totraverse the length of the belt span L, with the belt travel S andreturn against the belt travelS to the starting place. V is the apparentwave velocity as determined from the equation 2L s V V, is the resultantvelocity through space, increased when the wave travels in the directionwith the belt travel. V is the resultant velocity when the wave travelsin the reverse direction to the belt direction and is correspondinglydecreased. T, is the time required for the wave to travel the length L,with the belt motion S. T is the time required for the wave to travelthe, length L against the belt motion S. G is the acceleration ofgravity at location of the experiment. W is the weight per unit lengthof the stretched vibrating member.

F is the force of tension stretching said member. M is the mass ofweight by which the belt may be loaded when S is zero and it is desiredto ascertain W. T is the time of complete vibration of the belt soloaded.

Two point meth0d.In a still belt the chronograph record gives T, whenceL, the distance between the two points being known, V is computed fromEquation 1. W and G being known, F is computed from Equation 10. If thebelt is running, V and V are recorded according to the last members ofEquations 5 and 6 whence V and S are calculated according to Equations 7and 8. W and G being known and V and S determined as given above, thetension on the belt can be obtained from Equation 10 or the rate of workfrom Equation 11. If the weight, W, per unit length of belt is not knownand it is not desired to remove the belt for weighing, the standing beltof span of length L is vibrated with a single detector near its middleto get T, the time of a complete vibration of the free span. Then a massof known weight, M, is attached to the middle of the belt and a recordof the time, T of a complete vibration of the loaded belt taken (thetension F not having been appreciably altered) W is calculated fromEquation 12.

Single point meth00Z.The free length of belt span L found, the speed ofthe belt travel, S, is ascertained. The chronographic record of thedynamometer gives T as found by a detector placed near the middle of thebelt and Equation 4 is used to obtain V V and S applied to Equation 3gives the value of V. W is known or previously found as given above forapplying Equation 12. Applying the values of V and W to Equation 10gives the tension on the belt, while V, W and S applied to Equation 11gives the power or rate of work.

Several other methods may be used but the last described single pointmethod is found the most practical in most cases.

If English units be used then V and S are in feet per second, W is inpounds per foot, T, T, and T also T are in seconds. M is in poundsweight, F is in pounds stress and F S is in foot pounds per second.While G is usually about 32.2 feet,

FS horsepower.

.031 V W=stress on belt.

.00005 636 V W horsepower.

I claim as my discovery: 1. That improvement in the art of determiningthe amount of power transmitted by a traveling transmitting membercapable of vibration comprising the determination of the speed of travelof lateral vibrations in said transmitting member in the direction oftravel, and in the direction opppsite to the travel of the transmittingmember.

2. That improvement in the art of determining the amount of powerdelivered to a driven member by an endless traveling transmitting membercapable of vibration comprising the determination of the speed of travelof lateral vibrations along the tight and slack sides of thetransmitting member in the direction of, and in the direction oppositeto, the direction of travel of the transmitting member.

3. That improvement in the art of determining the amount of powerdelivered to a driven member by an endless traveling transmitting membercapable of vibration comprising the determination of the speed of travelof lateral vibrations along the tight and slack sides of thetransmitting member.

4. That improvement in the art of deter mining the amount of powertransmitted by a traveling transmitting member capable of vibration,comprising producing lateral vibrations in said transmitting member, anddetermining the speed of travel of said lateral vibrations in oppositedirections along said transmitting member.

5. That improvement in the art of determining the amount of powerdelivered to a driven member by an endless traveling transmitting membercapable of vibration, comprising producing lateral vibrations in thetight and slack sides of the transmitting member, and determining thespeed of travel of said vibrations along said tight and slack sides.

6. That improvement in the art of determining the amount of powerdelivered to a driven member by an endless traveling transmitting membercapable of vibration, comprising producing lateral vibrations in thetight and slack sides of the transmitting member, and determining thespeed of travel of said vibrations along said tight and slack sides inopposite directions.

In witness whereof, I, have hereunto set my hand and seal at Lawrence,Kansas.

LAWRENCE N. nonsense. [Ls] Witnesses:

I. J. MEADE, ARTHUR M. HooD.

copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. 0.

